Hi, I've seen the questions on the forum and here are my findings. These may or may not suit, but they are aimed at large sails and big pilots in the 5.6mtr wheelbase of a Lake Lefroy Mini yacht.

I was going to redo these ages ago on "Google sketchup" to look nice and neat, but I could easily build 2 new yachts quicker.
My students at the Ag college and I are learning it, but it's not coming easily to someone who has spent his life building gear from a sketch off the back of an envelope.

Here is the layout of "Fowl Play" that I sail with a 6.2m2 and 6.9m2 sail, in almost all winds. Wind speed, needs to be above 25knots to downsize to 5.5m2. I weigh in at 113kg, and I'm 183cm tall.

These plans are the changes I have made to a standard "Lake Lefroy Mini" plan, to perform with larger sails.
A standard LLM built exactly to Paul Days plans, as on Seabreeze Forum,
www.seabreeze.com.au/forums/Land-Yacht-Sailing/Construction/Build-a-Landyacht-Lake-Lefroy-Mini-Yacht/
performs perfectly, with the smaller sails it was designed to use.
I just push the envelope of the design and have arrived at these measurements with "Fowl play" which is the 22nd LLMini I've built. So a fair bit of trial and error has evolved into these measurements.

All my chassis are from bent galvanized street signs I pick up from our local shire yard for free.

From the plans below, I have now gone to a mast step angle of only 2 degrees, adjustable back to 10 degrees and have not used the rear settings on the mast base. ie; mast in its fully forward position for all sailing.

Also the seat base/back intersection, has been moved 75mm ahead of the centre line of the 35mm x35mm x2mm RHS rear axle.

If I built another, I wouldn't bother with the complexity of the adjustable fore and aft mast position, I would just make it adjustable for rake angle (Like Pacific Magic in the construction section of Seabreeze).
www.seabreeze.com.au/Articles/Land%20Sailing/Original-Pacific-Magic-Plans-by-Paul-Day_1514690.aspx

I am using a 6.9 m2 cammed sail on a 5350mm extended carbon mast. IMCS 29 with 1000mm of 4.5mm walled internal stiffener up the bottom. The top 150mm of this stiffener, has fingers cut into it, to relieve the stress point, and bonded in with silicon.

Hope this is of some assistance for the bigger fellas out there.



Just ignore the shim note on the photo below, as it is for my fitting into my jig I have.





The ratchet block is just stored here so I don't lose it. I use a 6 to1, "Crocket downhaul" system.

12mm all thread does the adjusting.




My rear axles have only 1 degree of camber now. 0.7 before I am seated in it. This snap below is the view from the rear of the axle. My yachts have gone from 8 down to 5 degrees of camber. "Saline by" was down to 3 degrees and was holding better when I used a 5.5 m2 sail. "Landyacht" suggested I go a bit further and they are now 1 degree. This works a treat for my rig. Tyre wear is very even and the back end is nailed to where I want it. When it lets go now, the world spins round big time. Last time at Lake Lefroy on very hard salt, I ran the left side at 1 degree and the right at 3 degrees for a couple of hours, just to see if I could tell the difference. Yes that's why I was back and forth across the pond on the same track for so long. There was a marked difference in the tyre noise and the 1 degree wins hands down on grip and = better speed. I just kept standing the mast up till it cornered well and the back didn't slide at all. It was a great couple of days to test things out and I tried to get as many people sailing it, for their ideas as well. Most comments were that 6.9 m2 isn't at all different to the smaller rigs, even in high winds it's very manageable.


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Fowl play has now done just over 2,100 GPS logged kms and had 3 chassis cuts/mods done.

PS; As a side note, Greg was back on Pink Lake this arvo sailing and said the surface was dead smooth. Shame we have more rain forecast for tomorrow.

Cheers Chook
(lots of edits, as my spelling is NOT good. )

Great post Chook

Ok Chook, a couple of questions to clarify your' modifications.

1. you have settled on a mast position, forward/aft, does this differ from the LLM'S specs?

2. With the bigger sails you are using very little mast rake, is there a relationship between the steep rake angle and moving the seat base forward?

3. Is reducing the camber a result of altering the mast set up and shifting the weight forward or is it related to pilot weight, (I'm wondering if the generous pilot weight places excessive side load on the single row bearings under straight running and if this would result in slower running between tacks)

Great post, I also have a generous amount of static ballast, so just deciding if this info should influence my LLM build. Do you have any comparative performance figures over a stock LLM with you piloting?


Mick.

My chassis has been extended so that the mast step is now a 150mm further forward from the back of the rear axle compared to the standard LLM.
I would most definitely try to shift my mast forward as much as possible 150mm if you could and use 3 to 5 degrees of rake on a fixed mast step. (3 for big sails light winds, 5 degrees for smaller than 5.5mt2. I have altered 5 standard LLM's to be 3 degrees and they perform well with 150mm added to their chassis and the seat/backrest intersection moved 75mm forward.)
The 150mm alteration is controlled by how tall you are to reach the steering pedals. A V shaped horizontal crossbar to take the pedals may be needed to clear the mast step in this position if you are not as tall. A child will need some cushions to move their bum forward in the seat.

The rear axle/chassis T, 35mm x35mm x2, on "Fowl play" has been widened by 30mm and with the wheels stood up to only 1 degree of camber the 30mm x 30mm x2mm axles, have been lengthened slightly as well. This increases the width of the yacht a bit as well.
A 1.6mm walled 25mmx 25mm RHS internal doubler, was added as I kept curving the axles.

I just kept fiddling round to see how much I could stretch the triangle and still fit the 6.5mtr Mini parameter. I believe that the original design of "Landyacht's" LLM, was taken from a blokarts wheelbase. So there is quite a bit of room to move and still fit the 6.5mtr rule. Please correct me if I'm wrong about this Paul.

With the bigger sails on my older standard LLM's, the centre of effort was WELL back and outside the envelope for positive steering. I have to slip well forward under the seat belt, to retain any sort of control. When the speed/power increased the back end would keep letting go and steering was really sketchy. I got slapped onto my side at speed a few times.

The mast was shifted forward in 50mm increments on my 2 previous yachts "Saltern" first 50mm, it made a difference and "Saline by" the move to 100mm was a marked improvement .
So I bit the bullet and built the adjustable mast step on "Fowl play" This took it to 150mm forward but still had the ability to shift it back and stand up the mast to 0 degrees of rake to experiment. This worked really well, so I then shifted the seat forward 50mm and then finally to 75mm for more weight on the front wheel, as now the rear end wasn't so loose and breaking out at all. Moving the mast and then the seat forward had loaded up the front wheel so it wont skate at all on hard salt and the softer gypsum I sail on at Pink Lake 2 kms from my home. I've had no need to shift the mast back towards me.

When Pink Lake is still drying out and much softer to sail on, I rake the mast back for slightly less load on the front wheel.

It's a very scientific measurement of how much mast rake is needed.
I just grab my water bottle and take a stroll back along my wheel tracks to see how much difference in the roost of disturbed soil, between the front wheel and the rears. I then adjust accordingly till the front and down wind tyre tracks look more or less even.
With my feet off the steering pedals, powered to the hilt, on a broad reach, sheeted in for dear life, I like just a hint of heading into wind.

Hard salt is down to the music the tyres are making, as they tell you the story really well. Also I like the back to break out, just before the front.

Camber was an interesting one and to be perfectly honest, I'm still not sure as to why 1 degree is so much better/faster. But the GPS doesn't lie. I sailed for a very long time with one wheel at 1 degree and the other at 3 degrees to compare the GPS track/speeds. Maybe it's the side load on the SKF bearings is less at 1 degree. It just doesn't make much sense, as with more side load more degrees you would think would be better. Please chime in here guys, I'd love to know.

Yes I still have my first yacht, "Code Red" and it's good to get back into it and see where it all started out, with a 5.5m2 cammed windsurfer sail on an extended fiberglass mast back in March 2011.

What I do know is, that a good pilot in any yacht, will still blitz me any day. With as much hooning round that I do, there is no replacement for actual racing conditions. I just don't have that killer instinct in me. I just come back with bugs in my teeth from grinning all day.
Its such great therapy for about $400.00. The pulley blocks are the greatest expense.

When I work my 2 days from home each week, my wife says I work from 8.00am till 12knots and I'm off kite buggying along the beaches, or land sailing if the conditions at the lake are favourable. 4 line stunt kites get a workout as well.

I just love this landsailing past time and get a kick out of taking my spare yachts to the lake and giving some new soul a touch of nature.
Landsailing, it's the worlds best kept secret.

Errrr you did mean a 5.6m rope loop to measure the yacht to be compliment with the 'International 5.6m Mini class'?

Ah yes I certainly did.

Thanks for that Gizmo........Bit of a dyslexic moment.
It's a bugger to get old.

Would love some other input fellas.
These are just my findings with no real scientific background, just trial and error (some days just lots of errors.) and some sound advice from the more senior sailors who's arms I can twist for more info.

" With the bigger sails on my older standard LLM's, the centre of effort was WELL back and outside the envelope for positive steering. I have to slip well forward under the seat belt, to retain any sort of control. When the speed/power increased the back end would keep letting go and steering was really sketchy."

Nice pictures and information. Thanks for posting. My mini has the same issues as above. Mast is in about the exact same place as yours but is raked at 11 degrees. I have an adjustable mast step as well but it's as far forward as possible and I like the rake as it is so the boom is as close to the deck as possible. I did some experimentation at the last regatta on the last day of racing. I flipped the axle upside down which raised the rear of the boat about 2.5''. It completely changed the steering by taking rake out of the mast and changing the ce location. Now instead of sketchy steering and rear end breaking loose It hiked a lot. Since then I've flipped the axle over into the original position and bought a smaller diameter front tire so the boat overall sits lower. It lowered the front about 1.625''. Hopefully that will be a nice compromise between the two. I just need to get a chance to do some testing.

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Chook2 said...

Camber was an interesting one and to be perfectly honest, I'm still not sure as to why 1 degree is so much better/faster. But the GPS doesn't lie. I sailed for a very long time with one wheel at 1 degree and the other at 3 degrees to compare the GPS track/speeds. Maybe it's the side load on the SKF bearings is less at 1 degree. It just doesn't make much sense, as with more side load more degrees you would think would be better. Please chime in here guys, I'd love to know.

This graphic is a bit crude and exaggerated but will give you an understanding of the proper loading of a radial roller bearing. The races are not shaped for the bearings in the horizontal position. Look at one that's apart, you'll see.

Just like tires, less surface area means less drag! Less drag means more speed!

We are talking about side loads <------- -----> not vertical loads as indicated by the arrow in your diagram. The loads are not carried by single bearings but pairs of bearings. These bearings can almost be considered as single units if spacers are used between the inner races which transfers the load between the bearings.

TP1, running the single row standard ball bearings with camber is a compromise, they are designed to be loaded at 90deg to the axis, paired or not used as wheel bearings they are subjected to axial loading equal to the sum of horizontal vectors of wind load and centrifugal loads when turning plus gravity when the axle has camber. Without camber the reduction in axial loading is reduced by the horizontal vector due to gravity. This is an additional loading exacerbated by increased weight of the operator but would require a lot of mathematics to determine just how much this affects resistance within the bearing. However the vector for a 120 Kg operator would be double that for a 60 kg operator.

Anyhoo ......... these axial loads will cause rolling resistance within the bearing . There are a couple of alternatives such as angular contact ball bearings, a lot more expensive or taper roller bearings with an inherent greater rolling resistance than a single row ball bearing and requiring preload and lubrication issues ie seals required.

I have read that some are removing the inner seals on the 6204 bearings and running light oil rather than grease. I suspect that this gives very marginal advantage at the upper end of performance but may in fact provide a greater advantage from a standing start. Of course any advantage could easily be negated by incorrect tyre pressure or wheel alignment.

I guess the only way to determine how much the axial loads affect performance would be to calculate the sum of horizontal vectors for a given situation, apply that as an axial load to a bearing and measure the torque difference required to rotate the bearing compared to the same load applied radially.


Fortunately I don't plan on any serious competition sailing so absolute performance is not a critical issue for me.

Mick

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Test pilot 1 said...
We are talking about side loads <------- -----> not vertical loads as indicated by the arrow in your diagram. The loads are not carried by single bearings but pairs of bearings. These bearings can almost be considered as single units if spacers are used between the inner races which transfers the load between the bearings.

No offense TP1 but,


Wrong!!

The position of the bearing dictates the load that is applied to it, not by how many there are or if they have sleeves between them. Even ten bearings in tandem all have different loads on them at any given time.

Spacers do not transfer loads between the bearings they are only for locating the inner race to prevent "crush" of the ball and race! That's why they are called "crush sleeves" not spacers!. If you install sleeves in your hubs you better turn the ends true on a lathe first to get the length and squareness of the ends perfect or it is detrimental to use a sleeve or spacer, as you call it.

No two bearings act as one even if they are right next to each other, unless you can time them by indexing (which is impossible). Besides there are different forces at play between the inside bearing and outside bearing of the wheel hub. Why do you think you see a larger diameter bearing on the inside of a car or truck hub???


The "horizontal" or "incorrect application" image does represent side load................

The bearing on it's side is the horizontal and the upright bearing is the vertical. The arrow in the diagram indicates the load direction for both horizontal and vertical loads, in two images. The wrong or horizontally installed roller bearing application has a greater coefficient of friction. If you disagree then take one apart and look at the inner and outer race grinds and compare it to the ball. You will see that a radial roller ball bearing is not designed to run horizontal but is designed for vertical loading only. There are other bearings for this application, They are called tapered roller bearings. They are designed for side, torsional and vertical loading, all at the same time.

This is a depiction of a cross section of a bearing in question.

So there it is Chook,

Radial roller bearing physics in a nut shell. Whether it's one degree or 90 degrees, it's not vertical.

Team wally covered it pretty well too.

I hope this leaves you without a doubt.

7302 angular contact bearing, unsealed 20mm I'd 52mm od x 15 mm wide $45 each, 6204 2 rs $7.00 each. Wild need to see a fair margin of performance gain to justify the price.

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TeamWally said...
7302 angular contact bearing, unsealed 20mm I'd 52mm od x 15 mm wide $45 each, 6204 2 rs $7.00 each. Wild need to see a fair margin of performance gain to justify the price.

The tolerances is what dictates the price of a bearing. For land yacht Wheel barrow wheels there is no advantage for the price. The 7302's are for spindle applications like rotating heads and the such. Way overkill and still the wrong application.

At the risk of becoming pedantic there ar spindle angular contact bearings and angular contact bearings, similar but different load angles! Still not worth the price.

A whole lot of really technical stuff about bearings and howntheybaremused.

medias.ina.com/medias/en!hp.tg.cat/tg_hr*ST4_1652155275

An interesting read with lots of pictures.

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KAONAONA said...

Test pilot 1 said...
We are talking about side loads <------- -----> not vertical loads as indicated by the arrow in your diagram. The loads are not carried by single bearings but pairs of bearings. These bearings can almost be considered as single units if spacers are used between the inner races which transfers the load between the bearings.

No offense TP1 but,


Wrong!!

The position of the bearing dictates the load that is applied to it, not by how many there are or if they have sleeves between them. Even ten bearings in tandem all have different loads on them at any given time.

Spacers do not transfer loads between the bearings they are only for locating the inner race to prevent "crush" of the ball and race! That's why they are called "crush sleeves" not spacers!. If you install sleeves in your hubs you better turn the ends true on a lathe first to get the length and squareness of the ends perfect or it is detrimental to use a sleeve or spacer, as you call it.

No two bearings act as one even if they are right next to each other, unless you can time them by indexing (which is impossible). Besides there are different forces at play between the inside bearing and outside bearing of the wheel hub. Why do you think you see a larger diameter bearing on the inside of a car or truck hub???


The "horizontal" or "incorrect application" image does represent side load................

The bearing on it's side is the horizontal and the upright bearing is the vertical. The arrow in the diagram indicates the load direction for both horizontal and vertical loads, in two images. The wrong or horizontally installed roller bearing application has a greater coefficient of friction. If you disagree then take one apart and look at the inner and outer race grinds and compare it to the ball. You will see that a radial roller ball bearing is not designed to run horizontal but is designed for vertical loading only. There are other bearings for this application, They are called tapered roller bearings. They are designed for side, torsional and vertical loading, all at the same time.

This is a depiction of a cross section of a bearing in question.

No offense KO but wrong
We don't use roller bearings only ball bearings and I don't see how showing a bearing at 90 degrees to the way it is used can explain anything . Spacers are indeed turned up on a lathe and we definitely don't crush them as we make them too solid for that.

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Test pilot 1 said...

No offense KO but wrong
We don't use roller bearings only ball bearings
Ya, Ya ,Ya ball bearings. I guess we all have to be right about something once in a while

and I don't see how showing a bearing at 90 degrees to the way it is used can explain anything.
As I said, I was exaggerating the angle for demonstrative purposes. I guess you missed the lesson there.

Spacers are indeed turned up on a lathe and we definitely don't crush them as we make them too solid for that.
In this application you would not need to crush them they are only for locating, not pre loading! The only concern here is that the length of the "spacer" has to match the distance between the inner races.

I've been wrong before! OOPS! there I go again!

Sorry Chook,

I'll leave your thread now. Seems to have diverted from your mods.

Sorry,
Kaona

No not at all Kaonaona. I like the different ways people think. All positive for the sport, I feel.

I do know for sure that there is a HUGE difference from the cheap bearings to the quality of the more expensive ones.
The last lot of cheaper bearings I was supplied with, didn't even have a recess on the inner race for the rubber seal to run in and the rubber seal didn't have any tin support in its inside side wall each side of the bearing either. Very nasty construction, but at a cheap price.
Old saying I guess, you get what you pay for.

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KAONAONA said...

Test pilot 1 said...

No offense KO but wrong
We don't use roller bearings only ball bearings
Ya, Ya ,Ya ball bearings. I guess we all have to be right about something once in a while

and I don't see how showing a bearing at 90 degrees to the way it is used can explain anything.
As I said, I was exaggerating the angle for demonstrative purposes. I guess you missed the lesson there.

Spacers are indeed turned up on a lathe and we definitely don't crush them as we make them too solid for that.
In this application you would not need to crush them they are only for locating, not pre loading! The only concern here is that the length of the "spacer" has to match the distance between the inner races.

I've been wrong before! OOPS! there I go again!

oops sorry i green thumbed you

TP1,

Green thumb??? I might be too old for that lingo because I don't know what that means!

Lame ha.

I followed Chooke's and the euro example of moving the mast post forward (I went 12") It made a huge difference to the yacht, I had to play around with the mast rake a little to get a nice balance in the mini. I set my wheels a 9% to more or less line up with the centre of effort of the sail(Both the mini and my class5 are set up like this), seems to work for me. But experimentation is what it is all about. The 5.6 rule allows for plenty of that

Just a little comment on the bearing spacers.

Unless the wheel hub is steel and the bearings are pressed in with a very tight (non-slip) fit, or else the hubs are fitted with end caps to lock the bearing in place, then the use of spacers to attempt to equally share side loads by both bearings is useless. If attempted, the spacer in that case needs to be only between the inner races and then machined exactly as per the width between the outer races. That is very hard to achieve with precision bearings. Most motor shafts have only one bearing "fixed or captive" with a stepped shaft to the second bearing. This allows the second bearing to "float" without preload which will destroy the bearing. So in actual fact only one bearing is ever taking the side thrust.

In the case of plastic hubs it is impossible to fit a bearing tightly to plastic so that it cannot move. So it is necessary to rely on only one or the other of the plastic inner hub shoulders to accept the side thrust. Therefore only one bearing is accepting side thrust at any time. Again, a spacer would not be of any use.

With the plastic hubs and plastic bearing adaptors it is very neccesary to use a spacer to lock the bearings together as the combined tolerances of the plastic parts allow the bearings to move independant to each other. Because of the flexibility of the different plastics involved, this can cause a slight wobble under side load and will lead to heating and softening of the plastic around the outer bearing race, with the final outcome being a chewed out bearing socket. Therefore both bearings share side load, distributing it over a larger area with less plastic distortion. I notice on my wheels a definite noise under side load unless I have spacers fitted and wheel nut done up tightly.
Side loading occurs on both bearings:- When right wheel is airborne, the left wheel has load on top of outer bearing and bottom of inner bearing. When left wheel is airborne, the right wheel has load on top of outer bearing and bottom of inner bearing. This only happens if both bearings are locked together with a spacer

Sorry "teepeewun" (good name for your yacht) but I don't agree about sharing side loading in one wheel. Firstly forget about the plastic adapter, they look neat but only make up the gap between bearing and hub to allow an incorrect and poorly seated bearing. They add to the problem by allowing the bearing outer to be less supported by the plastic wheel hub and I'm not impressed there. A steel adapter would be far superior.

I agree having a sleeve tightened between bearing inners does keep the alignment of the bearings true within the plastic hub - and that is worthwhile. But the side weight transferred from one bearing via the sleeve to the other is in turn transferred via the balls (pardon the expression) to the outer shell. That outer shell is still free to move out of the hub or the adapter and therefore cannot accept a side load.

In my opinion the Fallshaw plastic wheels are accurate mouldings and run true, machined spacer between inners races is good, but bearings and shaft sizes need to be selected to eliminate those plastic adaptors.

All of these factors are valid and can be proved with a little basic maths and physics, however, reality rules! The fact remains that the bearing wheel combinations have proved themselves workable in use. It is an unarguable fact that within the range of loads and setups being used by various land yachts the 6204 bearings are coping, and there are no reports in these forums of catastrophic failure or indeed unacceptably short service life.

Mick.

The fact is that the bearings are clamped together via the sleeve and axle. This changes the side loading to a more vertical force, down on the outer bearing and up on the inner bearing.
6204's are ideal bearing size and instead of changing bearing sizes for different wheels it is cheaper/easier to adapt the wheel to suit. This allows interchanging bearings where needed eithr between yachts/wheels or even sailors. besides the more who use the same size the cheaper easir itt is to buy in bulk.

wow the experts are out!!!!
my tests have shown that the plastic fallshaws with adaptors AND spacers are really great/ they are not a compromise as there isnt another wheel in Oz to compare in price or quality.
I use a 6004 bearing as the adaptor is a bit thicker and seats better.
spacers absolutely!!!!!